Stabilization of zein solutions



where the ketone or alcoh Patented July 31, 1945 UNITED STATE STABILIZATION OF ZEIN SOLUTIONS Hugh J. Hagemeyer, Jr.,

signor to Kinm t Kodak Company,

Team, as- Rochester,

N. Y., a corporation of New Jersey No Drawing. Application September, 1848, Serial N0. 502,320

SOlaims.

This invention relates to a stabilization of solutions of rein in aqueous acetone or aqueous alcohol by incorporating therein a small proportion of carbon disulflde.

Zein. the protein derived from corn, is unique among the commercially available proteins by virtue of the fact that it is soluble in many organic solvents. This makes it especially valuable for many purposes. In spite of the desirable properties of zein and the-large amount which is commercially available, that protein has never found wide application. This is thought to be due to the fact that zein solutions gradually increase in viscosity until a gel is formed. This change usually takes place within 24 to 48 hours and therefore, unless the solution is to be employed within a short time, it becomes unsuitable for use. In most cases the zeln solutions are illtered and also there may be various other processing steps before use such as mixing with added ingredients. By the time these operations are complete, the zein often has begun to gel and the solutions are of no value.

One object of my invention is to provide a method of reducing t e tendency of rein solutions to gel so as to make possible their storage for as much as to days without undergoing an appreciable change in viscosity. Other objects of my invention will appear herein.-

1 have found that incorporating a small proportion of carbon disulflde in the zein solution retards the characteristic of that solution to increase in viscosity and therefore the solution may be allowed to stand for 4 to 10 days without any appreciable increase in viscosity. My invention is particularly applicable to solutions of zein in aqueous lower aliphatic ketofies or aqueous monohydroxy lower aliphatic alcohols particularly o1 constitutes 85-90% of the. solvent. For example, a mixture of as parts of acetone and parts of water is one!- cellent solvent for zein forming a clear low viscosity solution or dope. This solution, however, will gel in about 48 hours without the presence of a stabilizing agent therein. Instead of a ketone,

an alcohol such as methyl, ethyl or isopropyl alcohol might be employed as the solvent for the zein and the same phenomenon occurs.

I Ordinarily it is only necessary to incorporate an amount of carbon disuliide 140% of the weight of the min, usually a concentration of 245% will give the desired stability. As a rule, the stability increases with the increase of concentration of carbon disulfide and. therefore. to obtain good stability at least 1% is desirable. In

- eratures up to 80 C. may

but the additional proportion serves no use cases, however, where the individual operator is satisfied with a partial retarding of the action of the zein solution, a proportion less than 1% might be employed. A proportion of carbon disulflde greater than 10% might be employfelg wasteful of carbon disulflde.

' The best results in stabilizing the zeln solutions have been obtained by partial warming of solution after adding the carbon disuliide. Tembe employed although temperatures within the range of 50-60 C. have been found to produce the desired effect. Usually it is desirable to continue the heating for although merely heating up to the purpose and is 'bilization has also been obtained by autoclavins the solution at time such as 1 to 15 minutes. autoclave, other meanssuch as refluxing may be employed to prevent the escape of solvent when heating at the higher temperatures. The following examples illustrate my invention.

Eromple 1 A solution was preparedhaving the following composition:

This solution stood for 6 days without any appreciable increase in viscosi A solution of the same composition, omitting the carbon disulfide, was found to gel in 24 hours.

Example 2 autoclaved for 5 minutes at C. The solution stood for 10 days without evidencing any change in viscosity.

trample 3 A solution was prepared having the following composition:

to stillbeothindope- The solution was warmed to 50? C. It was then set aside for 12 days and was found to still be of low viscosity at the end of that time.

Example 5 I A solution was made up as specified in the preceding example and this solution was autoclaved at 120 C. for 5 minutes. The solution was allowed to stand for 10 days and was found to still be of low viscosity liquid.

Zein solutions, in accordance with my invention, may be mixed with plasticizers, pigments,

dyes, filling materials or colloidal materials which are added to improve or alter the characteristics of. the solution. The solutions in accordance with my invention are adapted to the preparation of fibers or for coating surfaces therewith.

I claim:

1. A solution of zein in a mixture of water and a water-miscible solvent selected irom the group- "ing consisting of methyl alcohol, ethyl alcoh'ol,

isopropyl alcohol and acetone, containing therein carbon disulflde in an amount suilicient to retard increase of viscosity of the zeln solution upon standing.

2. A solution of zein in aqueous acetone contaming therein 2 to 5% of carbon disulfide based on the weight of the zein.

3. A solution of zein in aqueous alcohol containing therein 2 to 5% of carbon disulfide based on the weight 01' the zein.

HUGH J. HAG/MEYER, JR. 

